zita makra dvm sziu vet faculty equine department and clinic...
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Corneal ulceration
Nonulcerative keratitisCorneal stromal abscessEquine recurrent uveitisEyelid lacerations
Corneal ulcerationVery commonSight-threatening, corneal perforation!Etiology
opportunistic bacteria fungiStreptoc. Aspergillus,Staphyloc. spp. Fusarium spp.Pseudomonas aerug.
PathogenesisPathogenesis
1. Corneal epithel damage2. Bact./fungi → corneal epithel, corneal stromal fibroblast, tear
PMN→ inflammatory cytokines3. Corneal epithel cells, PTF neutrophil leukocytes→ proteinases,
elastase, collagenase4. Stromal destruction → melting ulcer
ClinicalClinical signssigns
♦pain (photophobia, blepharospasm, epiphora)♦anterior uveitis (miosis, cyclospasm, hypopion)♦corneal oedema
DiagnosisDiagnosis::-slit lamp biomicroscope-microbiological sampling → AB test-cytologic sampling→fungal hypha- Pas/Grocott stain-fluorescein dye
Descemetocele: fungi>bact., special fluorescein dyedanger of perforation → prompt surgical intervention
TherapyTherapy::
SPL:- AB (chloramphenicol, tobramycin, gentamycin, ciprofloxacin)
q2-6 h- antimycotic (natamycin, fluconazol, voriconazol): q4-6 h- antiproteinase: autolog serum + 0,1% EDTA/10%
acetylcistein q1-2 h- atropin 2% q4-6 h, decreasing dose- flunixin or phenylbutazone iv/po 5-7 days- (syst. Antibiotic)
Contraindicated: corticosteroids and local anesthetics
SurgicalSurgical interventionintervention::- superfitial, indolent: punctated/grid keratotomy- deep: debridement keratectomy / pedicle conj.flap +
amniotic membrane graft
Nonulcerative keratitis
1. Nonulcerative keratouveitis- sport horses- paralimbal stromal infiltration- uveitis- immune-mediated- corticosteroid and atropin subconjunctivally
- parenteral NSAID 2. Nonulcerative interstitial keratitis
- pigmentation3. Eosinophilic keratoconjunctivitis
- proliferation
Corneal stromal abscessEtiology:Epithelial cells cover (healed ulcer) encapsulated infectiousagents/foreign body in the stroma (Fluorsc.-)
Prominent yellowish opacity in the cornea + vascularisation + uveitis.
Therapy: see deep ulcer
Surgery:lamellar keratoplastypenetrating keratoplasty cornea transplantation
Equine recurrent uveitis (ERU)
Classic:- active phase+calm periods
Subclinical uveitis:- no observed bout of imflamm.(insidious) - chronic ERU (cataract, phthisis)
- Appaloosa, draft
Primarly posterior uveitis (Europian horses)
Equine recurrent uveitis (ERU)
Causes:1. Ocular insult- Trauma- Infectious (Leptospira, Strepto.)- Corneal disease
1.Episode acute uveitis Immune response-multiple recurrentepisodes-ERU
Uveitis results in the influx of inflamm. cells into the eye (Tly) persistent ly → hypersensitivity of uvea.
80 % unilateral, at 4-8 years of age 1. Uveitis
Complex pathophysiology:-non-specific multifocal origin
-individual genetic predisposition (MHC I. ELA-A9)
-immun-mediated recurrent/persistent panuveitis
-blood-aquous humor, blood-retina barriers break down
PathophysiologyPathophysiology::
Ag →blood-eye barrier ↓ → 1. Neutrophyls, 2. Ly-s in iris stroma, +serumproteines, fibrocytes, clotting factors in the aqueoushumor, vitreous, retina⇒serous-fibrinous inflammation + cellularinfiltration ∼ (Ly follicles)Type IV. late hypersensitivity reaction: TH1
Infectious agents/Ag get into the eye → 1. uveitisAg is permanently present in the eye →recurrent attacks
Ag-antibody complexImmunologically sensitized TH can become reactive due to
similar Ag/ autoantigen stimulus (S-Ag)
AcuteAcute clinicalclinical signssigns((activeactive phasephase):):
- photophobia, miosis- corneal edema- aq. flare, hypopyon- hypotony- chorioretinitis
ChronicChronic phasephase ((remnantsremnants--prepre--purchpurch. . examexam!):!):
- corneal edema- synechia posterior (iris bombae, pupillar occlusion)- pigment on the lens capsule, cataract, lens sublux. / lux.
(glaucoma)- peripapillary depigmentation
TreatmentTreatment::
- local corticosteroids (dexam. 3 mg / predn. 40 mg, triamcinolon 2mg subconj.)
- atropine (1 mg subconj., later 2% eyedrop/ointment)- corneal injury →cyclosporin / diclofenac- systemic NSAID
For 14 days, then must taper off dose +10 days
Important rule!Every painful, red (injected) eye needs to be stained withfluorescein to diagnose or ruleout corneal ulcers!
TreatmentTreatment::
Surgical: pars plana vitrectomy in the calm period:- to eliminate the recurrent inflammation- to save the eye bulb- to improve the vision
Surgical TreatmentTreatment::
bioerodible, sustained release of CsA-immunosuppressant, deep scleral lamellar cyclosporineimplant, against cell-mediated immunity
Eyelid lacerations:
Emergency Correct anatomical reposition!
References
D.E. Brooks: Ophthalmology for Equine Practitioners2nd ed., Tenton Newmedia, Jackson, WY
K.N. Gelatt: Essentials of Veterinary Ophthalmology1st ed., Lippincott W&W, Philadelphia, 2000.
B. Gilger: Equine Ophthalmology2nd ed., Elsevier Saunders, Missouri, 2011.
K.N. Gelatt: Veterinary Ophthalmology3rd ed., Lippincott W&W, Philadelphia, 1999.
Equine Ophthalmology Supplement 2.EVJ, Nov., 1983.
Equine Ophthalmology Supplement 10.EVJ, Sept., 1990.
J.D. Lavach: Large Animal Ophthalmology, CV Mosby, St Louis, 1990.